Improvement in removing acid from the surface of i ron



UNITED STATES D. MGDANIEL, OF NEW PATENT OFFICE.

CASTLE COUNTY, AND E. A. HARVEY, OF WIL- LIINGTON, DELAWARE.

Specification forming part of Letters Patent No. 33,844, dated December 3, 1861.

ing it.

The nature of our invention and improvements in removing acid from iron previous to galvanizing, painting, rerolling, or working consists in ingyn ing it under a vacuum or partial vacuum, or immersing and boiling under a vacuum or partial vacuum the sheets or articles of iron from which the acid is to be removed or cleaned in a solution of soda, lime, caustic soda, or some solution which will neu tralize the acid previously applied to the iron; also, the urging or forcing, by means of liquid, steam, or atmospheric pressure, the neutralizing-solution of soda, lime, caustic soda, or such other solution as will neutralize the acid previously applied to the iron, into the pores or interstices in theiron to more effectually accomplish the purpose than has heretofore been done.

To prepare sheet or other article of iron for coating with other metals, painting, rerolling, or working, we first remove the scale or oxide from its surface by immersing it in dilute acid, consisting of about one gallon of sulphuric or muriatic acid, or of a mixture of both. these acids, to forty gallons of water. We keep the iron in the dilute acid until the scale and oxide can be readily removed by washing and brushing, and then rinse the iron well in clean water. After rinsing we place the iron in a strong vessel, capable of resisting a strong or heavy pressure from either the outside or inside, and provided with a cover which may be readily secured air-tight, in which vessel is a solution consisting of about one pound of caustic soda to twenty gallons of water, or a solution consisting of about one pound of lime to six gallons of water, secure the cover air-tight and exhaust the air .by some convenient means, and make a vacuum of about from ten to fourteen pounds per square inch, and then boil the solution for half an hour for small article and longer for large, up to two hours.

After boiling we subject the iron while in the solution to a pressure of from one to six atmospheres, very porous iron requiring a heavy pressure. will answer. This pressure should be continued about half an hour, or until the neutralizingsolution has penetrated all the pores and interstices in the iron to the samedepth or extent that the acid did to neutralize the acid previously used as effectually and as per-' fectly as possible. We now remove the iron from the solution and place it in clean water, and wash it thoroughly and dry it, when it is ready for coating with metal, painting, rerolling, or other subsequent process of finish or foruse.

We are aware that other preparations or compositions of acid may be used to remove the scale and oxide from the iron. we do not limit ourselves to the use of those described; and there may be other neutralizing-mixtures besides those described which may answer the purpose. Therefore we do not limit ourselves to the use of the mixture described, but intend to use such mixtures as will best answer the purpose.

We believe we have described the improved process of removing acid from iron which we have invented or discovered so as to enable any person skilled in the art to perform or use it, and we will now state what we desire to secure by Letters Patent.

We claim- 1. The improved process for removing acid from sheets and other articles of iron describedto wit, immersing the sheets or articles of iron under a vacuum or partial vacuum, or immersing and boiling under a vacuum or partial vacuum the sheets or articles of iron from which the acid is to be removed or For sound iron less pressure Therefore cleaned in a solution of soda, lime, or caustic previously'applied to the iron, into the pores or soda, or in some solution which Will neutralize the acid previously applied to the iron. D. MODANIEL.

2. Urging 0r forcing, by means of liquid, E. A; HARVEY. steam, or atmospheric pressure, the neutral- Witnesses:

DANL. H. KENT, W..E. TUcH'roNE.

interstices in the iron.

izing-solution of soda, lime, caustic soda, or such other solution as will neutralize the acid I 

